Electric indicator



(No Model.) 2 Sheets-Sheet 1. J HOPKINSON ELECTRIC INDICATOR.

Patented Jan 13 WITNESSES:

INVENTOR.

N D 5 m K P n. H N H G JV (No Model?) 2 Sheets-Sheet 2.

. J. HOPKINSON.

ELECTRIC INDICATOR.

No. 444,552. Pa te nted Jan. 13, 1891.

a if: [QQI c 0 Q WITNESSES: INVENTOR,

1 dm-m HEIPKINSDN. QWM 1 w Att'y.

UNTTED STATES PATENT OFFICE. f

JOHN HOPKINSON, OF HOLMVOOD, ENGLAND, ASSIGNOR, BY MESNE ASSIGN- MEN TS,TO THE VVESTIN GI-IOUSE ELECTRIC AND MANUFACTURING COM- PANY, OFPITTSBURG, PENNSYLVANIA.

ELECTRIC INDICATOR.

SPECIFICATIOH forming part of Letters Patent No. 444,552, dated January13, 189-1.

Application filed February 23, 1889. Serial No. 300,846, (No model.)Patented in England July 27, 1882, No, 3,576.

To all whom, it may concern: pensating for the drop or loss may bedeter- Be it known that 1, JOHN I'IOPKINSON, a mined by properlyadjusting the relative ofsuloject of the Queen of Great Britain,residfects of the two coils of the indicator.

ingin Holmwood,Wimbledon Common, S.\V., In the accompanying drawingsthere is \Vestnnnster Chambers, England, have in shown in diagram inFignrel an organization vented a new and useful Improvement in ofapparatus for carrying out the invention.

Electric Indicators, (Case No. 279,) (for which Fig. 2 is a diagramshowing the application Letters Patent of Great Britain No. 3,576, ofthe coils to an indicator.

bearing date of July 27, 1882, have been Referring to the figures, Arepresentsady- [O granted to me,) of which the following is anamo-electric machine, and N lamps or other specification. translatingdevices of any suitable character My invention relates especially toapparaconnected in multiple are between the contus for determining thedifference of potential ductors L L leading from the terminals ofexisting at a given point in a system of electhe machine.

I 5 tric circuits supplying translating devices, the The indicatingapparatus is represent-ed at special object being to provide anindicator C. It is constructed with two coils c c opposin which thevarying drop or loss of potential ing each other. The one coil 0 isconnected upon a circuit may be readily compensated across the poles ofthe generatorAor between for at all times. the lines L L at the points Eand F. This 20 When current is supplied by means of main coil is of linewire and has a comparatively 7o conductors to points more or lessdistant from large number of convolutions. The second a central station,there is a fall of potential, coil 0 is of thick wire, havingcomparatively due to the resistance of the conductors, and fewconvolutions. It is connected either dias the current flowing increasesthe fall of rectly in one of the conductors L or L orin a 25 potentialalso increases, so that if it is desired circuitderived therefrom, sothat either the to maintain a constant difference of potential wholecurrent or a proportional part thereof at the distant points specialmeans must be will pass through it from the point G to the employed fordetermining the loss under any point H. The current passing through thegiven load. To accomplish this I employ an coilc opposes in effect thatthroughthe shunt- 0 indicator wound with two opposing coils, one coil 0.I usually prefer to use a proportional of comparatively high resistanceand conpart of the currentrather than all the current nected across theterminals of the source'of passing through the lineL It is then easy byelectricity and the other of low resistance, so properly adjusting therelative resistance of connected as to be traversed by all or a deterthetwo circuits including the two coils to in- 3 5minateproportionalpartoftheourrent flowing dicate the compensationrequired for any tothe translatingdevices. If, now, the current givenvalue of resistance of themain lines flowing totheworkcircuiti11crcases,theeifect and thus secure a constant differenceof poof the series coil increases correspondingly. tential between thetwo conductors at the dis 1f the difference of potential at theterminals taut point. The shunt-coil 0 may be made 40 of the sourcebemaintained atanormal value, of German silver for the purpose ofpreventthe dili'erence of potential at the terminals of ing it fromvarying materially in its resist the translating devices will not be asgreat as ance; but this is not necessary. before, because of the greaterloss or drop The differential apparatus may assume upon the circuitwhich accompanies the various different forms without departing 4 5transmission of the increased current, so'that from the essentialfeatures of the invention. in order to maintain the proper difference ofIt may be arranged to indicate directly to the potential upon thework-circuit it is necessary eye when the value of the difierence of poto increase the difference of potential at the tential upon thework-circuit requires regu terminals of the source. The increase indiflation.

5o ference of potential thus required for com- It will be evident thatan increase of our rent flowing to the mainline will increase the effectof the coil 0' of the indicator, thereby tending to correspondinglyoperate the indicator. If no change takes place in the difference ofpotential at E F, then the indicator will be thrown out of balance. Theincreased effect of the series coil 0" in theindicator may be balancedby increasing the difference of potential between the points E and F. Byproperly ad justing the relative effects of the two coils, therefore,the additional difference of potential required to bring the indicatorto its normal position may be made to exactly compensate for theincreased drop upon the line, sothat the difference of potential at theterminals of the translating devices will be maintained approximatelyconstant if the index of the indicator is kept in a normal position.

I claim as my invention- 1. In an indicator, differentially-wonndconductors, one designed to be connected in shunt upon the work-circuitand the other in series therewith, substantially as described.

2. The combination, with a source of electricity and a work-circuitsupplied therefrom, of an indicator having two opposing coils, oneconnected in shunt upon the work-circuit and the other in seriestherewith, substantially as described.

The combination of a source of electricity, translating devices suppliedtherefrom, and an indicating apparatus for determining the difference ofpotential upon the work-circuit, consisting of two opposing coils, onereceiving currents proportional to the difference of potential at theterminals and the source and the other receiving currents proportionalto the current delivered to the work-circuit, and an indicatoroperatedby the resultant effects of the currents traversing the two coils.

In testimony whereof I have hereuntosubscribed my name this 9th day ofFebruary, A. D. 1889.

JOHN .IIOPKINSON.

Witnesses:

CRANSON, E. A. HALL, Clerks to JlIessrs. John Newton (12' Sons-,9 Birchin Lane, London, Public Notaries.

